The present invention relates generally to the control and pumping of liquids and gasses, hereafter called fluids, in very small regions, and more particularly to micro valves and micro pumps.
It is useful to control fluids in small regions. For example, micro pumps that can be implanted under the skin for the delivery of medicine for patients or the manipulation of pressurized fluids to control micro surgical instruments used in endoscopic and labrascopic surgery, or the fluidic control of micro chromatography systems used to detect undesirable elements in the environment or for controlling samples such as blood and chemical reagents to build a complete analytical system that can perform analysis in a physician""s office or in the field, or for controlling the flow of small particles or devices entrained in a fluid, or for use as a controller for a microair table to float and move devices, or as a rapid acting fluidic switch that can control larger valves that control the flow of larger amounts of fluids.
These devices can be made by a variety of micro fabrication methods, including silicon fabrication techniques such as silicon surface machining and silicon bulk machining and wafer bonding and etching and deposition and also with non-silicon fabrication technologies such as LIGA (German for Lithographie, Galvanoformung, and Abformung or in English X-ray lithography, electroforming and molding processes) or EDM machining (Electro Discharge Machining) or plating or molding or stereolithography or a number of other technologies familiar to researchers in the field of micro fabrication.
Micro valves tend to leak because it is difficult to form a good micro valve seat. As the valve gets smaller, there is less material in the valve seat, and it is quite easy to scratch or crush one of these micro valve seats. Further, current micro valves have limited application because they are not capable of regulating fluid flows at high pressures.
Thus, there is a need for a micro valve having a good micro valve seat, and further, being capable of regulating fluid flows exerting high pressure loads.
The present invention is directed to a microelectromechanical valve having two or more diaphragms containing non-aligned holes to control the flow of fluids. Fluid flows through the holes in the first diaphragm and then must flow between the first and second diaphragm to reach the holes in the second diaphragm, whereupon the fluid is free to flow past the second diaphragm.
In a presently preferred embodiment, valve comprises a first diaphragm in spaced opposed relationship to a second diaphragm. The diaphragms comprise offsetting holes such that fluid flow between the diaphragms is impeded when the diaphragms are in close proximity to one another and fluid flow through the diaphragms is enabled when the diaphragms are spaced apart, and an actuator for causing the diaphragms to approach and retract relative to each other.